On Sun, Nov 27, 2022 at 06:00 PM, David Brostoff wrote:
Besides the large discrepancy in total shared DNA, the fact that on Ancestry your mother and Mary do not share one of their MyHeritage triangulated matches makes me ask whether you are certain that the Mary on Ancestry is the same as the one on MyHeritage.I've been in touch with Mary, initially through MyHeritage messages, and she pointed me to her test on Ancestry. And we've compared the matches.
I guess it is possible that the much smaller match between Mary and my mother on Ancestry might result to an even smaller match with those who have shared matches on MyHeritage, small enough to fall below Ancestry's threshold. Note that the 25cM largest segment on dropped to a 15cM largest segment on Ancestry. Since the shared matches were from my generation, I'd expect the match numbers to be about half. If Ancestry excludes segments smaller than 7, that might explain the missing triangulated matches.
Of course, along the lines suggested by your question, if the matches are so radically different, what are the chances that something more serious went wrong?
Lee David Jaffe